Efficiency

In your research trying to understand solar power, you feel like solar panel efficiency is something you should be able to easily grasp. Efficiency should be easy to understand, right? Except the deeper you dig, the more confused you get. What’s the difference between solar cell efficiency and solar panel efficiency? Who can you trust when it comes to solar efficiency?

I got an email from someone purchasing solar panels from a supplier asking the difference between these two efficiencies. Helping people understand questions about solar is the whole point of this website, so after I answer a question via email – it often ends up here so that more people can learn.

Here’s the question:

My prospective supplier states that the Schuco 210 watt SMAU-1 panel has a cell efficiency of 16.8%, whereas your table gives a panel efficiency of 14.93%. What is the difference between panel and cell efficiency and which should be my guide?

So, the Sun shines on Earth and in that sunshine there is energy. Plants convert that energy into mass because energy is mass. E = mc2. Energy equals Mass times a constant (which is not important here). We eat the plants for energy, or we eat animals that eat the plants. That’s how we survive.

Simple Explanation:

Well, solar panels are humans’ attempt at making “plants” that convert the Sun’s energy into energy we use – to heat, chill, or light our homes, to power our TV’s, fridges, computers, etc. Well, it’s not easy converting that sunshine into energy we can use. And as it turns out, most solar panels convert 12-15% of the Sun’s energy that falls on the panel. The Sun dumps ~1,000 W/m2 at sea level on a clear day (source: wikipedia).

Solar panel efficiency is simple, but there a few things you need to understand.

There are 3 main types of solar efficiency.

1. Module Efficiency2. Area Efficiency (Density)3. Cell Efficiency

1. Module efficiency measures how well a solar module (aka panel) converts the Sun’s energy into usable energy. If the Sun dumps 100 Watts of energy onto the module and the module spits out 15 Watts, the the module is said to have 15% module efficiency (15 W / 100 W = 0.15 = 15%). If you want to brag to your friends that you have a top tier efficiency panel, care about this.

To simplify solar efficiency further, we have divided all modules into 5 tiers based on their efficiency compared to all other solar panels. Now installers and consumers can easily communicate about module efficiency. Are the solar panels in the most efficient tier (Tier 1) or do they have average efficiency (Tier 3)? If modules are in the least efficient tier (Tier 5), let’s hope they’re cheaper than the modules in the above-average tier (Tier 2).

If you have limited space and need to get the most energy for your area, then you need the most efficient solar panels for your project. People always ask me, “which panels have the highest efficiency?” or, “which solar PV panels are the best?” The truth is that solar panel efficiency isn’t as important as you might think. For most homeowners, the better question to ask is, “which panels will give me the most electricity for the best price?” You can find out how much solar might cost for your home by using our free solar calculator. But you’re here to find out the most efficient solar panels, so let’s get on with it.

The most efficient solar panel in 2016 is the SunPower SPR-X22-360 with a 22.07% panel efficiency.

Below is a solar panel comparison chart comparing the solar panel efficiency of all other modules rated at 360 watts like the SPR-X22-360. The 360 watt rating means that in strict laboratory conditions, these solar panels produce the same output. However, because solar panels vary in size, some end up being more efficient compared to others – meaning they can produce the 360 watts using less space (area).

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